JP-A-61-213056 discloses a method for forming a porous ceramic film on a ceramic substrate plate. The term "JP-A" as used herein means an "unexamined published Japanese patent application". In this method, calcium phosphate prepared by the wet process is pre-calcined at about 500.degree. to 1,000.degree. C. to prepare powder, subsequently a part of the raw powder is mixed with a binder and formed into a shaped article having a predetermined shape and the balance of the powder is mixed with another binder to provide a slurry, and then the slurry is coated on the above-obtained shaped article, followed by being dried and calcined. However, this method is disadvantageous because the production cost is high due to the use of the binders.
Further, JP-A-62-297284 discloses a method of forming a calcium phosphate film by flame spraying. This method, however, is defective in that the bonding strength of the film to the substrate is low and pore diameter is difficult to control.